This invention relates to determining an amount of data that has been read from a storage medium while a data transfer is in progress.
When reading data from a storage medium, such as a hard disk, a device driver reads the requested data, called “demand data”, optionally along with speculative data from other locations on the hard disk. The data from the other locations is called “prefetch data” and corresponds to addresses on the hard disk that are likely to be read next by the device driver (typically contiguous/sequential data).
Like reference symbols in the various drawings indicate like elements.